1. Field of the Invention
This invention relates to valved closure units for containers. Such closure units are widely used in beer kegs and the units are arranged so that the containers may be emptied and filled through the closure units.
Such a closure unit, hereinafter referred to as being of the kind specified comprises a bush arranged to be received in an opening in a container or keg, the bush normally being externally threaded near one end for threaded insertion into an internally threaded neck on the container, a downtube supported by the bush for extending into the container and spring-loaded valve means within the bush and associated with the downtube.
When the unit is used in a beer keg, the valve means are arranged to control the entry of carbon dioxide and the exit of beer from a full keg. Moreover, the valve means can be used to control the entry and exit of washing liquid and/or steam during washing of the keg and the entry of beer during filling of the keg. Normally, the valve means will be one of two types. The valve means will either comprise two concentric valves, one for beer and one for gas, each of the valves being separately spring loaded, or there may be a single valve member controlling separate beer and gas passages.
2. Description of the Prior Art
Heretofore, the bush of a closure unit of the kind specified has been made as a one-piece casting of stainless steel or aluminium or as a hot brass stamping and subsequently machined where necessary, the machining including producing a valve seat on the bush for the valve means and an external screw thread. Where the bush is of brass it has been chrome plated and where it has been of aluminium it has been anodised and epoxy coated. Such bushes of stainless steel are satisfactory but they are expensive and tend to pick-up when threadedly engaged in stainless steel neck fittings. However such bushes have good corrosion resistance. Chromed brass bushes do not pick up but the plating deteriorates and is damaged in use. Anodised and epoxy coated aluminium bushes do not pick up but are more susceptible to damage than chromed brass bushes.
It is one object of the present invention to provide improved forms of bush for such a closure unit.
These improved forms of the bush may have an inturned flange which provides a seat for the valve means or a valve member. While the seat is satisfactory it gives little or no guidance during movement of the valve member towards and away from the seat and misalignment may occur.
Moreover, in some known closure unit constructions, when the keg is being washed with the valve means at the bottom of the keg, the valve means forms pockets for the retention of washing liquid. This is undesirable.
It is another object of the present invention to provide a closure unit which overcomes these two problems.